The invention relates to a vehicle of the kind having a body pivoted to the vehicle frame in such manner as to enable the body to rock about a substantially horizontal axis and permit the contents of the body to be dumped. Raising and lowering movements of the body are effected by means of an extensible and retractable ram having a cylinder within which is a plurality of telescoping piston sections. In conventional constructions one end of the ram is pivoted either to the body or to the vehicle frame and the other end of the ram is pivoted to the frame or to the body so that extension of the ram will cause the body to swing upwardly about its pivotal connection to the frame. Vehicles of the kind with which the invention is concerned include bodies such as those manufactured by Edbro Incorporated, Orland Park, Ill., and Perfection-Cobey Co., Galion, Ohio, among others. Extensible and retractable rams suitable for use with such bodies are available from the aforementioned manufacturers, from Hyco, Inc., Ashland, Ohio, and others. A typical ram suitable for use in the aforementioned environment is illustrated in Wood et al U.S. Pat. No. 2,854,958.
Although the means known heretofore for coupling rams between the vehicle frames and the dump bodies often function well in the raising and lowering of such bodies, they do have certain disadvantages. For example, when an unloaded vehicle has its body in a lowered position and is driven at speed over rough terrain, railroad tracks, and the like, it is not uncommon for that end of the body to which the ram is coupled to vibrate or bounce vertically. If the pivotal connection between the ram and the body is rigid, the vertical vibration is transmitted to the seals between the ram cylinder and its piston, thereby subjecting the seals to excessive wear and premature failure. If the pivotal connection between the ram and the body or vehicle frame is of the pin and slot type so as to provide for lost motion, the clearance between the pin and the end of the slot either is insufficient to compensate for vertical vibration or promotes excessive noise with corresponding wear of parts.
Another disadvantage of pivotal couplings of the kind referred is that they oftentimes are subjected to lateral forces caused by uneven loading of the vehicle or by the vehicle's being on uneven terrain during body-hoisting operations. This is true even if the pivotal connections of the body to the vehicle frame do not allow for relative vertical movement of the opposite sides of the body, for the reason that the body itself is capable of limited torsional or twisting movements from one end to the other. In those instances in which the body is subjected to lateral torsional or gravitational forces, the rigid pivotal connections between the ram, the body, and the vehicle frame are subjected to severe stresses which may result in failure.
An object of the invention is to provide coupling means for coupling an extensible and retractable ram between a vehicle frame and a vertically swingable body and which overcomes the disadvantages referred to above.